To grow plants in environments that have ambient temperatures unsuitable for the particular type of plants being grown, it is known to provide means for heating or cooling the air around the plants. For example, this may be achieved by suitably positioned heaters or by shading the plants from the glare of the sun, for example as is achieved through the use of polytunnels. A problem with known heating arrangements is that heating of the ambient air around the plants requires large amounts of energy.
It is also known to cultivate plants in a column of growing containers, examples of which can be found in U.S. Pat. No. 6,840,008B1, US2003/0089037A1, U.S. Pat. No. 5,555,676 and US2006/0156624. Water and nutrients may be fed into the columns of plants. However, there is no disclosure of how to control the temperature and flow of air around the plants.